The present invention relates to objective systems for photographic apparatus, and more particularly to improvements in objective systems which comprise variable-focus or zoom lenses. Still more particularly, the invention relates to objective systems having variable-focus lenses and means for focussing during the making of exposures at close range or at a greater distance (including infinity) from the subject. As used in the specification and claims, the term "objective system" is intended to denote a variable-focus lens, a tubular barrel or mount for the lens, and means for moving selected optical elements of the lens with respect to the barrel in the direction of the optical axis.
It is already known to provide an objective system for use in motion picture cameras with a variable-focus lens and with a rotary ring-shaped selector which can be displaced by means of a radially extending handle. When the handle is moved in a direction to rotate about the optical axis, the selector changes the focal length of the lens. In order to enable the selector to allow for focussing at close range, the handle is moved in the direction of the optical axis whereby such movement of the handle does not influence the positions of the optical elements but merely serves to disengage the selector from a further ring-shaped member which is connected with the optical elements of the lens. When the axial movement of the selector with the handle 1 is completed, the selector is rotated again to thereby focus prior to the making of exposures at close range. Such rotation causes a predetermined axial adjustment of certain optical elements of the lens.
It is further known to provide an objective system which includes a variable-focus lens with a selector which is rotatably and axially movably mounted on the barrel for the optical elements. When the selector is rotated in one axial position, it changes the focal length of the lens. Rotation of the selector in another axial position results in focussing prior to the making of exposures at close range.
Each of the just described prior solutions employs a single selector which must be rotated for the purpose of changing the focal length as well as for the purpose of focussing at close range. As a rule, the selector must be provided with a relatively wide annular knurled portion so that it may be readily gripped and conveniently manipulated by the user prior to and/or during picture taking. This is not possible when the selector is relatively small (e.g., if the manufacturer wishes to reduce the overall dimensions of the photographic apparatus) and/or when the selector is partly or nearly fully concealed in a forwardly extending part (e.g., a sleeve) of the camera body. In such instances, the selector is invariably provided with a radially extending handle which replaces the aforementioned knurled portion and enables the user to move the selector axially and/or about the axis of the lens.